Apparatus for making mixtures of nitric and sulfuric acids.



PATENTED NOV. 1 0, 1903.

P. I. DUPONT. APPARATUS FOR MAKING MIXTURES 0F NITRIC AND SULFURIG ACIDS.

APPLICATION FILED DEG. 26, 1902.

N0 MODEL.

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W TNESSES:

ret ted November 10, 1903.

PATENT OFFICE- FRANCIS I. DU PONT, OF WILMINGTON, DELAWARE.

APPARATUS FOR MAKING MIXTURES OF NIIRIC AND SULFURlC AClDS.

SPECIFICATION forming part of Letters Patent No. 743,922, dated N oveniber 10, 1903. Application filed December 26, 1902. Serial No. 136,523. (No model.)

To all whom, it may concern:

Be it known that I, FRANCIS I. DU Pour, a citizen of the United States, residingin the city of \Vilmingtomcounty of Newcastle,and State of Delaware, have invented certain new and useful Apparatus for Generating and Condensing Acids and other Substances; and I do hereby declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which My invention relates to apparatus for generating and condensing acids and other substances, but particularly to apparatus for generating nitric-acidfumes and for producing mixtures of nitric and sulfuric acids.

My invention consists in the introduction of circulating-conduits connecting-an acidgenerator with a condensing-chamber and arranged to convey fumes from the generator to the condensing-chamber and to return unabsorbed gases from the condensing-chamber to the generator and generally in the features hereinafter set forth in the claims.

The objects of my invention are to improve acid generating and condensing apparatus, and particularly apparatus for producing mixtures-of nitric and sulfuric acids, such as are used in making nitrocellulose, to render the apparatus efficient, to avoid the escape of uncondensed acid fumes, and to prevent corrosion of the apparatus by the fumes evolved. 1

I will now proceed to describe my inven tion with reference to the accompanying drawings, in which one form of apparatus embodying my invention is illustrated, and will then point out the novel features in claims.

In the said drawings, Figure 1 shows a vertical section of the apparatus. Fig. 2 shows a top viewthereof.

The apparatus illustrated in the drawings comprises a retort or generator 1, located within a furnace 2, a condensing-chamber 3, and conduits connecting the retort and condensing-chamber, as hereinafter described. The retort is provided with a charging-opening a and with a discharging opening 5, through which residue remaining in the retortupon the conclusion of the operation may be removed. Both of these openings may be closed in any suitable or ordinary manner during the operation of the apparatus. The furnace by which the retort may be heated may be of any customary or ordinary construction and requires no detailed description.

The condensing-chamber 3 or absorber, as it may also be called, contains during the operation of the apparatus a body of liquid 6, which will condense and absorb the fumes generated in the retort 1. Said condenser is provided with cooling-coils 7, through which a cooling medium may be circulated to keep this liquid 6 cool, and a stirrer'8, arranged to be driven in any suitable or well-known way,

may also be provided to keep the liquid" thoroughly mixed. The retort l is connected with the condensing-chamber 3 by means of a discharge-pipe 9 and a return-pipe 10,which together constitute a circulating-conduit. In one of these pipes, preferably in the returnpipe, is a blower 11, or other suitable device for maintaining circulation of the gases.

The condensing-chamber 3 is provided with a cock 12, through which the mixed acids may be drawn OE, and with an opening 13,

through which charges of absorbing acid may I be introduced. It is also provided with a safety-vent 14, provided with a check-valve 15, which prevents entrance'of air into the condensing-chamber through said opening, but permits the escape of gas from the condensing-chamber when pressure exists therein. Such opening serves to permit escape of gas when the air and gas within the chamber expands as a result of increase in temperature in the chamber and as a result of partial displacement of the air by vapors from the retort.

Iwill describe the operation of my apparatus as the same is used in producing mixtures of nitric and sulfuric acids. In this process a mixture of nitrate of soda and sulfuric acid is placed within the retort 1 and sulfuric acid is introduced into condensing-chamber 3 un til the latter is about half filled, the blower 11 is operated to cause a current of air to cir culate back and forth between the two tanks, and heat is applied to the retort, while a cooling medium is circulated through the coils 7. The nitric-acid fumes as they are generated are carried away rapidly by the currents of air produced by the blower 11 and are projected against the surface of the sulfuric acid in chamber 3 and are to a great extent condensed thereby. Such gases as are not condensed and absorbed are drawn back through pipe 10 by the blower 11, are passed through the retort 1, are there mixed with a further quantity of nitric-acid fumes, and are forced through the pipe 9 back into the condensingchamber.

It will be seen that with this apparatus the escape of acid fumes is to a great extent prevented, because only those fumes escape which remain in the apparatus at the conclusion of the operation and are practically non-condensible in the liquid within vessel 3. The use of the blower 11 greatly facilitates the evolution of nitric-acid fumes in the retort, rendering the operation of the apparatus very rapid.

It is obvious that the apparatus herein described is susceptible of various variations and modifications Without departing from the spirit and scope of my ihvention, and I do not limit myself to the particular construction herein illustrated and described.

In another application for Letters Patent, executed concurrently herewith, I have claimed the process of generating and condensing acid fumes above described.

An important advantage of this process and of the apparatus above described is that since the sulfuric acid keeps the air and gases in the apparatus perfectly dry the nitric-acid fumes will not attack the pipes 9 and 10 and otherparts of the apparatus with which said fumes come in contact if these parts be of iron. This greatly increases the strength, simplicity, and durability of the apparatus and makes it relatively inexpensive.

What I claim is 1. In an apparatus for obtaining mixtures of nitric and sulfuric acids, the combination with a retort, of an absorber, a conduit con: necting the same for conveying fumes from the retort to the absorber, a return-conduit connecting said absorber and retort, arranged to discharge the returned unabsorbed gases into said retort, and means for maintaining circulation of gases from said retort through said outgoing-conduit absorber, and returnconduit, into and through the retort.

2. In an apparatus for obtaining mixtures of nitric and sulfuric acids, the combination with a retort for generating nitric acid, and an absorber for containing sulfuric acid, of circulating-conduits connecting said retort and absorber, and arranged to return the unabsorbed gases, and a blower in said circulating-conduit.

In testimony whereof I affix my signature in the presence of two Witnesses.

FRANCIS I. DU PONT.

Witnesses:

REBA J. CoYLE, CLIFFORD V. MANNERING. 

